1. Field of the Invention
The present invention relates to an automatic envelope processing apparatus and method, and, more particularly, to such an apparatus which removes completed envelopes from an envelope folding machine, maneuvers them such that their folded-down top seal flap is placed upward, and deposits them in a horizontal stack on a receiving surface. A pair of cooperating movable supports then compresses individual stacks, each containing a predetermined number of envelopes, and positions them for a mechanical gripper to grasp the compressed stacks, lift them without bottom support and move them to another location for a further operation, such as packaging.
2. Description of the Related Art
Envelope manufacturing in general has increasingly become a highly automated operation. In the production of standard and specialty envelopes, large, complex machines serve to fold blanks, apply patches, and place adhesive on the side and top or seal flaps. The side flaps are folded over and sealed and the finished envelopes are normally output via a delivery spider into a horizontal stack on a surface, such as a conveyor belt, to be accumulated into stacks of envelopes for other operations, such as loading into cartons.
These accumulating and loading steps have been difficult to fully automate, thus usually requiring hand operations. In the past, conventional delivery spiders have fed the finished envelopes onto the delivery surface with the folded seal flap facing downward. As these envelopes with downward facing folded seal flaps accumulate on the receiving surface, the cumulative outward acting horizontal spring effect caused by the extra paper layers in the downward facing folded seal flaps tends to spread or expand the envelope stack longitudinally outward at the bottom. No gripping or picking machine is known which is capable of reliably automatically picking up the requisite number of envelopes from the horizontal stack and moving them away from the stacking area without dropping them. This is due to the "spring" action of the extra paper layers represented by the folded, open seal flaps which tends to bow the envelope stack outward at the bottom edges, causing envelopes in the middle of the stack to bulge downwardly and drop out, usually followed by the remainder of the stack.
As a result of this inability to design a suitable machine, and as further described below, it has been traditional for human workers to physically grasp the horizontal stacks of envelopes, carefully compensating for the greater bulk at the bottom, and lift them for transfer to a desired location, such as an open carton. There are a number of problems inherent in this arrangement. First, the use of manual labor is expensive, when compared to automated equipment. Second, the workers themselves face the same problem with the envelope stacks, i.e., once they are picked up by compressing the stacks inwardly from the ends, the spring action of the downward facing folded seal flaps tends to cause envelopes to loosen at the bottom and drop out. This means that the workers must manually exert a considerable compensating force inward against the bottom edges of the envelope stack, effectively squeezing the stack bottom to prevent the stacks from falling apart as they are lifted. Often the workers find it easier to turn the stack 180 degrees so the seal flaps are facing up, but the turning operation itself is difficult and likely to cause the stack to disintegrate. The handling of the stacks leads to the third problem, which is that these repetitious manual lifting, squeezing and turning motions, when repeated hour after hour and day after day, frequently cause the affected workers to develop carpal tunnel syndrome. This is an extremely painful nerve, muscle and ligament irritation in the wrists and hands which can cause temporary and even permanent disability in the workers. In addition to the problem of the resulting pain and suffering, these injuries represent a considerable financial strain in the form of workmen's compensation, lost wages, sick leave, etc. to an envelope manufacturer.
It is clear then, that a need exists for an automated apparatus which is capable of effectively and reliably off-loading stacks of envelopes from a receiving surface, accumulating, counting, and picking up predetermined numbers of the envelopes in horizontal stacks from the surface, and transferring them to other locations during the manufacturing/packaging process. Such an apparatus should be capable of reliably picking up and loading the stacks of envelopes, i.e. the apparatus must solve the problem of the bottom spring action caused by the loading of envelopes with downward facing folded envelope seal flaps.